Method of manufacturing osb with acoustic dampening properties

ABSTRACT

A manufacturing process for manufacturing wood products with acoustic dampening properties. A noise-dampening polymer is introduced in-line in the manufacturing process to achieve higher acoustic performance. The polymer can be a viscoelastic polymer which is added during blending of the lignocellulosic strands prior to mat formation, or sprayed or otherwise coated on the lignocellulosic strands during mat formation, prior to formation of any boards or panels.

This application is a continuation of U.S. patent application Ser. No.15/832,327, filed Dec. 5, 2017, which claims benefit of and priority toU.S. Provisional Application No. 62/429,896, filed Dec. 5, 2016, and isentitled to those filing dates for priority. The specifications,figures, and complete disclosures of U.S. Provisional Application No.62/429,896 and U.S. patent application Ser. No. 15/832,327 areincorporated herein in their entireties by specific reference for allpurposes.

FIELD OF INVENTION

This invention relates to a method and system for manufacturing woodproducts (such as OSB, oriented strand board) with acoustic dampeningproperties.

BACKGROUND OF THE INVENTION

Acoustic comfort is important in building design. Noise is the often theprimary complaint by home-owners in residential single-family homes, andnoise reduction also is an important performance criterion inmulti-family and commercial construction (particularly in the healthcareand education segments). Airborne noise/STC (Sound Transmission Class)rating and impact noise (Impact Insulation Class, IIC) rating in walland floor or ceiling assemblies often is specified in codes andstandards by ANSI, IgCC and LEED.

Airborne noise from outside or inside the living space has beenaddressed with various field-applied and pre-fabricated noise dampeningconstructions products, such as resilient channels, clips, staggeredstuds, multiple layers of drywall, wall cavity insulation, and laminatedacoustic drywall. Acoustic materials have been used to laminate twopanels of various building materials through a secondary process toimprove acoustic performance. However, there are no building materials,such as OSB-based siding, sheathing, roofing or flooring, thatincorporate a sound dampening material in the primary manufacturingprocess of panels with improved acoustic performance.

SUMMARY OF THE INVENTION

In various exemplary embodiments, the present invention comprises amethod or process for manufacturing wood products with acousticdampening properties. The manufactured wood product include, but are notlimited to, oriented strand board (OSB), LSL, MDF, particleboard, orvarious wood composites. The system introduces a noise-dampening polymerin-line in the manufacturing process to achieve higher acousticperformance (e.g., STC and IIC rating) in siding, sheathing, roofing,flooring, and similar applications using the manufactured wood product.The polymer can be a viscoelastic polymer which is added during blendingor formation of the wood product. In one exemplary embodiment, asdescribed in greater detail below, viscoelastic polymer is added to thecenter strand layer during the OSB manufacturing process.

General elements of the OSB manufacturing process include the drying andstoring of wood strands, the treatment or blending of designated strands(e.g., bottom, core, top) with applicable chemicals or additives (e.g.,wax, resin binders, and the like) the forming of the appropriate layersin order (first bottom surface, then core, then top surface) usingdesignated strands, the application of heat and pressure to the mats toform boards, and subsequent processing (e.g., panels cut to size, edgessealed, and packaging) to produce the finished product.

In a first embodiment of the manufacturing process, the core strands arecoated with the noise-dampening polymer in a strand blender or blender.The polymer can be blended with the core strands separately, or alongwith other additives typically added during the OSB process, such aswaxes or resin binders. These treated core strands are used to form thecentral layer, sandwiched between the bottom surface and top surface.The finished product is an OSB panel with a central layer with corestrands blended with the noise-dampening acoustic material or materials.This coating by blending can also take place for strands in otherlayers.

In another exemplary embodiment, the noise-dampening acoustic materialor materials are applied through a spraying, flow, curtain, or othercoating process in the forming line before, during or after the centerstrand layer is laid on the forming line. This coating can also takeplace for strands in other layers.

The finished product is an OSB or manufactured wood panel with a centrallayer with core strands (and possibly other layers) integrally coated,permeated or infused with the noise-dampening acoustic material ormaterials.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a view of a system in accordance with an embodiment of thepresent invention.

FIG. 2 shows another system in accordance with another embodiment of thepresent invention.

FIG. 3 shows another system in accordance with another embodiment of thepresent invention.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

In various exemplary embodiments, the present invention comprises amethod or process for manufacturing wood products with acousticdampening properties. The manufactured wood product include, but are notlimited to, oriented strand board (OSB), LSL, MDF, particleboard, orvarious wood composites.

In several embodiments, the present invention comprises a system forintroducing a noise-dampening polymer in-line in the manufacturingprocess to achieve higher acoustic performance (e.g., STC and/or IICrating) in siding, sheathing, roofing, flooring, and similarapplications using the manufactured wood product. The polymer can be aviscoelastic polymer which is added during blending or formation of thewood product. In one exemplary embodiment, as described in greaterdetail below, viscoelastic polymer is added to the center strand layerduring the OSB manufacturing process.

General elements of the OSB manufacturing process in accordance with thepresent invention, as seen in FIGS. 1 and 2, include the drying andstoring of wood strands 10, the treatment or blending of designatedstrands (e.g., bottom, core, top) with applicable chemicals and/oradditives (e.g., wax, resin, and the like) 30, the forming of theappropriate layers in order (first bottom surface, then core, then topsurface) using designated strands, 30, 40, 50, the application of heatand pressure to the mats using a primary press to form boards 60, andsubsequent trimming 70 and processing (e.g., panels cut to size, edgesprimed/sealed, and packaging) 80 to produce the finished product 100.Strands for a particular layer typically are blended with applicablechemicals and/or additives in a bin, separate from strands for otherlayers, although this is not always the case. Examples of primaryprocesses are described in U.S. Pat. Nos. 6,461,743; 5,718,786;5,525,394; 5,470,631; and 5,425,976; all of which are incorporatedherein in their entireties by specific reference for all purposes.

FIG. 2 shows an embodiment of the manufacturing process where the corestrands are coated with the noise-dampening polymer in a strand blenderor blenders 120. The top and bottom surface strands are blendedseparately 20 a, although in some embodiments, one or both sets ofstrands also may be blended with a noise-dampening polymer. The polymercan be blended with the core strands separately, or along with otheradditives typically added during the OSB process, such as waxes or resinbinders. The treated core strands are used to form the central corelayer 140, sandwiched between the bottom surface and top surface. Thefinished product is an OSB panel (or other manufactured wood product)with a core layer with core strands blended with the noise-dampeningacoustic material or materials. The heat and pressure applied during theprimary pressing process promotes the noise-dampening acoustic materialto integrally coat, permeate or infuse the core layer, and in severalembodiments, portions of the bottom and/or top surface layers.

FIG. 3 shows another second embodiment of the manufacturing processwhere, after blending of the strands 20 a, b, the noise-dampeningacoustic material or materials are applied through a spraying, flow,curtain or other coating process 240 in the forming line before, during,or after the center core strand layer is laid on the forming line. Thefinished product is an OSB panel (or other manufactured wood product)with a central layer with core strands coated with the noise-dampeningacoustic material or materials. As described above, the heat andpressure applied during the primary pressing process promotes thenoise-dampening acoustic material to integrally coat, permeate or infusethe core layer, and in several embodiments, portions of the bottomand/or top surface layers.

The components and parameters of the above processes can vary. In oneexemplary embodiment, the wood strands can be derived from hard (e.g.,aspen) or soft (e.g., southern yellow pine) woods, and can be homogenous(i.e., single wood type) or mixed, and green (moisture content fromabout 30% to about 200%) or dried (e.g., moisture content up to about12%) (where moisture content %=(weight of water in wood/oven-dry weightof wood)×100). Binders include, but are not limited to, isocyanateresin, urea-formaldehyde, phenol formaldehyde, melamine formaldehyde,bio-adhesives, or combinations thereof. In one embodiment, polymericisocyanate resin (pMDI, or polymeric diphenylmethane diisocyanate) isused at about 1.2 to about 20 weight %. Waxes include, but are notlimited to, a molten wax or emulsion was (in one embodiment, up to about2.5 weight %). Other chemicals or additives may be used, including, forexample, fire retardants, weather-resistant chemicals, or the like.Viscoelastic polymer is added as described above to the center layer orany other layer in the mat. Press time is from 1 to 20 minutes at atemperature from about 100° C. to about 240° C. The resulting panel canrange in thickness from about ¾″ to about 7″, and in density from about25 pcf to about 60 pcf (pounds per cubic foot).

In any of the above embodiments, the thickness and/or density of the topor bottom strand layer, or both, can be modified as well to achieve animproved acoustic performance/STC rating. The present invention thusprovides an OSB or manufactured wood panel with a noise-dampeningpolymer introduced in-line, with a resulting increase (1) in acousticperformance as compared to a standard OSB panel, and (2) in efficiencyand reduction in cost compared to secondary manufacturing processes. Thenoise-dampening polymer becomes integrated with, and infuses orpermeates the layer or layers of the panel.

In several embodiments, the noise-dampening of the present inventionapplies to both airborne sound transmission loss and impact soundinsulation. In some embodiments, panels produced in accordance with thepresent invention smooth airborne sound transmission loss curves in theASTM E90 test method, particularly increasing loss (dB) in frequencyranges where sound is transmitted more effectively due to physicalcharacteristics (i.e., of a similar panel but without thesound-dampening agent). In one embodiment, the present inventionincreases airborne transmission loss in the sound frequency ranges offrom about 1.5K to about 4K Hz (more particularly, from about 2K toabout 3.2K Hz, or even more particularly, from about 2.5K to about 3.15KHz).

In additional embodiments, panels produced in accordance with thepresent invention demonstrate increased impact sound insulation anddecreased sound pressure levels. In one embodiment, such panels have atested apparent impact insulation class (AIIC) rating in the range fromabout 26 to about 34, as determined by ASTM Standard E-1007 (2016). Incontrast, a control panel without noise-dampening polymer had an AIICrating of 19.

Thus, it should be understood that the embodiments and examplesdescribed herein have been chosen and described in order to bestillustrate the principles of the invention and its practicalapplications to thereby enable one of ordinary skill in the art to bestutilize the invention in various embodiments and with variousmodifications as are suited for particular uses contemplated. Eventhough specific embodiments of this invention have been described, theyare not to be taken as exhaustive. There are several variations thatwill be apparent to those skilled in the art.

What is claimed is:
 1. A method for producing a noise-dampeningmanufactured wood product, comprising the steps of: treating a set ofcore layer lignocellulosic material with one or more chemicals oradditives; treating, in a manufacturing production line, the set of corelayer lignocellulosic material with a noise-reducing polymer, whereinthe noise-reducing polymer does not form a homogenous layer; forming amulti-layer mat of lignocellulosic material, said multi-layer matcomprising a core layer comprising the treated set of core layerlignocellulosic material; applying heat and pressure to the multilayermat to produce a noise-dampening manufactured wood product.
 2. Themethod of claim 1, wherein the noise-dampening manufactured wood productcomprises one or more boards or panels.
 3. The method of claim 1,wherein the noise-dampening manufactured wood product comprises aoriented strand board panel.
 4. The method of claim 1, wherein themulti-layer mat comprises three layers.
 5. The method of claim 4,wherein the three layers are a top layer, a bottom layer, and the corelayer therebetween.
 6. The method of claim 5, further comprising thesteps of: treating a set of top layer lignocellulosic material with oneor more chemicals or additives; and treating a set of bottom layerlignocellulosic material with one or more chemicals or additives.
 7. Themethod of claim 6, wherein the step of forming a multi-layer mat oflignocellulosic material comprises the steps of: forming, in theproduction line, the bottom layer from the set of bottom layerlignocellulosic material; forming, in the production line on the bottomlayer, the core layer from the set of core layer lignocellulosicmaterial; and forming, in the production line on the core layer, the toplayer from the set of top layer lignocellulosic material.
 8. The methodof claim 1, wherein the step of treating the set of core layerlignocellulosic material with the noise-reducing polymer comprisesblending the polymer with the core lignocellulosic material prior toformation of the core layer.
 9. The method of claim 1, wherein the stepof treating the set of core layer lignocellulosic material with thenoise-reducing polymer comprises spraying, flowing, curtain coating orotherwise coating the core layer with the polymer.
 10. The method ofclaim 7, further comprising the step of treating the set of bottom layerlignocellulosic material with the noise-reducing polymer.
 11. The methodof claim 7, further comprising the step of treating the set of top layerlignocellulosic material with the noise-reducing polymer.
 12. The methodof claim 1, wherein the noise-reducing polymer is integrated with thelignocellulosic material forming the core layer.
 13. The method of claim1, wherein the lignocellulosic material comprises strands.